This project creates an occupancy counter that tracks how many people are in a room. Using two PIR sensors placed at a doorway, the system detects direction of movement (entry vs. exit) and maintains a count of current occupants. The count is displayed on an LCD and can be sent to a server for occupancy monitoring.<\/p>\n
Difficulty:<\/strong> Intermediate Two PIR sensors are placed at the top and bottom of a doorway (or left and right). When a person passes through, the order in which the sensors trigger indicates direction:<\/p>\n The system maintains a running count of people in the room, displayed on an LCD. An ESP32 can send occupancy data to a server or cloud platform.<\/p>\n For remote monitoring, use an ESP32 and send occupancy data to a server:<\/p>\n This occupancy counter provides accurate, real-time room occupancy data. It’s ideal for meeting rooms, shared workspaces, and any area where capacity management is important. With Wi-Fi integration, occupancy data can be accessed remotely and used to optimize space utilization.<\/p>\n","protected":false},"excerpt":{"rendered":" Project Overview This project creates an occupancy counter that tracks how many people are in a room. Using two PIR sensors placed at a doorway, the system detects direction of movement (entry vs. exit) and maintains a count of current occupants. The count is displayed on an LCD and can be sent to a server […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-3905","post","type-post","status-publish","format-standard","hentry","category-projects"],"blocksy_meta":[],"yoast_head":"\r\n
\nEstimated time:<\/strong> 3-4 hours
\nEstimated cost:<\/strong> $30-40<\/p>\nHow It Works<\/h2>\n
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Materials Needed<\/h2>\n
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Circuit Diagram<\/h2>\n
Connection Table<\/h3>\n
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\n \nComponent<\/th>\n Pin<\/th>\n Arduino Pin<\/th>\n<\/tr>\n<\/thead>\n \n Sensor A (Entry)<\/td>\n VCC<\/td>\n 5V<\/td>\n<\/tr>\n \n Sensor A (Entry)<\/td>\n GND<\/td>\n GND<\/td>\n<\/tr>\n \n Sensor A (Entry)<\/td>\n OUT<\/td>\n Digital Pin 2<\/td>\n<\/tr>\n \n Sensor B (Exit)<\/td>\n VCC<\/td>\n 5V<\/td>\n<\/tr>\n \n Sensor B (Exit)<\/td>\n GND<\/td>\n GND<\/td>\n<\/tr>\n \n Sensor B (Exit)<\/td>\n OUT<\/td>\n Digital Pin 3<\/td>\n<\/tr>\n \n LCD (I2C)<\/td>\n VCC<\/td>\n 5V<\/td>\n<\/tr>\n \n LCD (I2C)<\/td>\n GND<\/td>\n GND<\/td>\n<\/tr>\n \n LCD (I2C)<\/td>\n SDA<\/td>\n A4 (SDA)<\/td>\n<\/tr>\n \n LCD (I2C)<\/td>\n SCL<\/td>\n A5 (SCL)<\/td>\n<\/tr>\n \n Reset Button<\/td>\n One pin<\/td>\n Digital Pin 4 (with 10k pull-up)<\/td>\n<\/tr>\n \n Reset Button<\/td>\n Other pin<\/td>\n GND<\/td>\n<\/tr>\n \n Green LED<\/td>\n Anode<\/td>\n Digital Pin 5 (through 220\u03a9)<\/td>\n<\/tr>\n \n Green LED<\/td>\n Cathode<\/td>\n GND<\/td>\n<\/tr>\n \n Red LED<\/td>\n Anode<\/td>\n Digital Pin 6 (through 220\u03a9)<\/td>\n<\/tr>\n \n Red LED<\/td>\n Cathode<\/td>\n GND<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Arduino Code<\/h2>\n
#include <Wire.h>\n#include <LiquidCrystal_I2C.h>\n\n\/\/ Pin definitions\nconst int sensorA = 2; \/\/ Entry sensor (outside)\nconst int sensorB = 3; \/\/ Exit sensor (inside)\nconst int resetButton = 4;\nconst int ledGreen = 5;\nconst int ledRed = 6;\n\n\/\/ LCD (16x2, I2C address 0x27)\nLiquidCrystal_I2C lcd(0x27, 16, 2);\n\n\/\/ Variables\nint occupancy = 0;\nbool sensorATriggered = false;\nbool sensorBTriggered = false;\nunsigned long sensorATime = 0;\nunsigned long sensorBTime = 0;\nunsigned long lastEventTime = 0;\nconst unsigned long eventWindow = 2000; \/\/ 2 seconds to pair triggers\nconst int maxOccupancy = 50; \/\/ Safety limit\n\nvoid setup() {\n Serial.begin(9600);\n \n \/\/ Initialize pins\n pinMode(sensorA, INPUT);\n pinMode(sensorB, INPUT);\n pinMode(resetButton, INPUT_PULLUP);\n pinMode(ledGreen, OUTPUT);\n pinMode(ledRed, OUTPUT);\n \n \/\/ Initialize LCD\n lcd.init();\n lcd.backlight();\n lcd.setCursor(0, 0);\n lcd.print(\"Occupancy Counter\");\n lcd.setCursor(0, 1);\n lcd.print(\"Initializing...\");\n \n Serial.println(\"Occupancy Counter Starting...\");\n Serial.println(\"Waiting 60 seconds for sensor warm-up...\");\n delay(60000);\n \n updateDisplay();\n Serial.println(\"System Ready\");\n}\n\nvoid updateDisplay() {\n lcd.clear();\n lcd.setCursor(0, 0);\n lcd.print(\"People in room:\");\n lcd.setCursor(0, 1);\n lcd.print(\" \");\n lcd.setCursor(5, 1);\n lcd.print(occupancy);\n \n \/\/ Update LEDs\n if (occupancy > 0) {\n digitalWrite(ledGreen, HIGH);\n digitalWrite(ledRed, LOW);\n } else {\n digitalWrite(ledGreen, LOW);\n digitalWrite(ledRed, HIGH);\n }\n \n Serial.print(\"Occupancy: \");\n Serial.println(occupancy);\n}\n\nvoid processEntry() {\n occupancy++;\n if (occupancy > maxOccupancy) occupancy = maxOccupancy;\n Serial.println(\"Entry detected (+1)\");\n updateDisplay();\n}\n\nvoid processExit() {\n occupancy--;\n if (occupancy < 0) occupancy = 0;\n Serial.println(\"Exit detected (-1)\");\n updateDisplay();\n}\n\nvoid checkTriggers() {\n unsigned long now = millis();\n \n \/\/ Check sensor A (entry)\n if (digitalRead(sensorA) == HIGH && !sensorATriggered) {\n sensorATriggered = true;\n sensorATime = now;\n Serial.println(\"Sensor A triggered\");\n }\n \n \/\/ Check sensor B (exit)\n if (digitalRead(sensorB) == HIGH && !sensorBTriggered) {\n sensorBTriggered = true;\n sensorBTime = now;\n Serial.println(\"Sensor B triggered\");\n }\n \n \/\/ Determine direction if both triggered within window\n if (sensorATriggered && sensorBTriggered) {\n if (abs((long)(sensorATime - sensorBTime)) < eventWindow) {\n if (sensorATime < sensorBTime) {\n \/\/ A first, then B = entry\n processEntry();\n } else {\n \/\/ B first, then A = exit\n processExit();\n }\n }\n \/\/ Reset trigger flags\n sensorATriggered = false;\n sensorBTriggered = false;\n }\n \n \/\/ Timeout: clear single triggers after window\n if (sensorATriggered && (now - sensorATime > eventWindow)) {\n sensorATriggered = false;\n Serial.println(\"Sensor A timeout - ignored\");\n }\n if (sensorBTriggered && (now - sensorBTime > eventWindow)) {\n sensorBTriggered = false;\n Serial.println(\"Sensor B timeout - ignored\");\n }\n}\n\nvoid loop() {\n \/\/ Check reset button\n if (digitalRead(resetButton) == LOW) {\n delay(50);\n if (digitalRead(resetButton) == LOW) {\n occupancy = 0;\n updateDisplay();\n Serial.println(\"Occupancy reset to 0\");\n while (digitalRead(resetButton) == LOW) {\n delay(10);\n }\n }\n }\n \n checkTriggers();\n delay(50);\n}\n<\/code><\/pre>\nESP32 Version with Wi-Fi Data Logging<\/h2>\n
#include <WiFi.h>\n#include <HTTPClient.h>\n\nconst char* ssid = \"YourWiFiSSID\";\nconst char* password = \"YourWiFiPassword\";\nconst char* serverURL = \"http:\/\/yourserver.com\/api\/occupancy\";\n\nvoid sendOccupancyData() {\n if (WiFi.status() == WL_CONNECTED) {\n HTTPClient http;\n http.begin(serverURL);\n http.addHeader(\"Content-Type\", \"application\/json\");\n String payload = \"{\\\"occupancy\\\":\" + String(occupancy) + \"}\";\n int httpCode = http.POST(payload);\n http.end();\n }\n}\n\n\/\/ Call sendOccupancyData() after each occupancy change\n<\/code><\/pre>\nInstallation Steps<\/h2>\n
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eventWindow<\/code>. If slowly, increase.<\/li>\nCalibration Tips<\/h2>\n
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Troubleshooting<\/h2>\n
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Project Extensions<\/h2>\n
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Conclusion<\/h2>\n